The present invention relates to a device for supporting an ultrasonic vibration assembly including an ultrasonic vibrator and an ultrasonic vibration transmitter coupled to the vibrator.
FIG. 2 is a longitudinally sectional view of a device for supporting an ultrasonic vibration assembly, which was disclosed in Japanese patent application Kokai No. 63-193699 owned by the same assignee and published on Aug. 10, 1988.
In FIG. 2, an ultrasonic vibrator 1 generates ultrasonic vibration and is shaped as a column. An ultrasonic vibration transmitter 2 is coupled to the bottom of the ultrasonic vibrator 1 coaxially thereto. A tool 3 is coupled to the bottom of the transmitter 2 so as to perform machining by using ultrasonic vibration. Flanges 4a and 4b, which function as pistons, are provided on the outside circumferential surface of the transmitter 2 near the top and bottom thereof integrally with the transmitter. A cylinder 5 includes the flanges 4a and 4b so that the flanges are slidable up and down in the axial direction of the cylinder. Mechanisms 7a and 7b feed a pressurized fluid such as pressurized air to spaces 6a and 6b defined between the flanges 4a and 4b and both the ends of the cylinder 5, and have feed pipes 8a and 8b which extend from a pressurized fluid source (not shown) and are connected to the spaces and provided with control valves 9a and 9b which are regulated independently of each other. An opening 11 is provided in the cylinder 5 so that a space 10 between the flanges 4a and 4b in the cylinder is connected to the exterior thereof.
The operation of the device shown in FIG. 2 will be described. When the control valves 9a and 9b are opened, the pressurized fluid such as pressurized air is fed from the pressurized fluid source to the spaces 6a and 6b so that the vibration assembly including the ultrasonic vibrator 1 and the vibration transmitter 2 is floatingly supported. The vibrator 1 is then driven by AC power so that the vibrator generates the ultrasonic vibration corresponding to the frequency of the AC power. The ultrasonic vibration is transmitted to the tool 3 through the ultrasonic vibration transmitter 2 so that the tool performs the ultrasonic machining on a workpiece. At that time, the flanges 4a and 4b provided on the transmitter 2 integrally therewith undergo the ultrasonic vibration, but the friction between the inside surface of the cylinder 5 and the flanges is very low. For that reason, the ultrasonic vibration assembly is freely slidable in the direction of the ultrasonic vibration and freely rotatable about the axis of the assembly, which extends in the direction of the ultrasonic vibration. Even if the resonance frequency of the vibration system changes, since the transmitter 2 is floatingly supported in the cylinder 5 so as to be a resonator having no fixedly supported end, nothing hinders the ultrasonic vibration of the transmitter 2. Therefore, the power of the ultrasonic vibration transmitted by the transmitter does not undergo a loss.
A difference can be set between the pressure of the fluid in the space 6a and that of the fluid in the other space 6b so as not only to support the ultrasonic vibration assembly but also to optionally set the pressure of the ultrasonic machining on the workpiece.
If the amplitude of the ultrasonic vibration of the assembly supported by the device is to be increased in transmitting the vibration to the tool 3, a vibration enlarger 12 is coupled to the bottom of the vibration transmitter 2 coaxially thereto under the bottom of the cylinder 5, as shown in FIG. 3, so that the enlarger transmits the ultrasonic vibration from the transmitter to the tool coupled to the bottom of the enlarger, while increasing the amplitude of the vibration, to cause the tool to perform the ultrasonic vibration of the increased amplitude.
If the vibration enlarger 12 is coupled to the bottom of the vibration transmitter 2 to increase the amplitude of the ultrasonic vibration, as shown in FIG. 3, the length of the ultrasonic vibration assembly is increased and the movability of the assembly at the tool 3, in the direction perpendicular to the vibration, is increased. This is a problem.